/div>Country, Middle East, southwestern Asia. Area: 636,374 sq mi (1,628,750 sq km). Population: (2009 est.) 74,196,000. Capital: Tehran
. Persians constitute the largest ethnic group; other ethnic groups include Azerbaijanians, Kurds
, Lurs, Bakhtyari, and Baloch. Languages: Persian (Farsi; official), numerous others. Religions: Islam (official; predominantly Shi'ite); also Zoroastrianism. Currency: rial. Iran occupies a high plateau, rising higher than 1,500 feet (460 metres) above sea level, and is surrounded largely by mountains. More than half of its surface area consists of salt deserts and other wasteland. About one-tenth of its land is arable, and another one-fourth is suitable for grazing. Iran's rich petroleum reserves account for about one-tenth of world reserves and are the basis of its economy. It is a unitary Islamic republic with one legislative house and several oversight bodies dominated by clergy. The head of state and government is the president, but supreme authority rests with the rahbar
(leader), a ranking cleric. Human habitation in Iran dates to some 100,000 years ago, but recorded history began with the Elamites c.
3000 BCE. The Medes flourished from c.
728 but were overthrown in 550 by the Persians, who were in turn conquered by Alexander the Great
in the 4th century BCE. The Parthians (see Parthia
) created an empire that lasted from 247 BCE to 226 CE, when control passed to the Sasanian dynasty
. Various Muslim dynasties ruled from the 7th century. In 1501 the Safavid dynasty
was established and lasted until 1736. The Qajar dynasty
ruled from 1796, but in the 19th century the country was economically controlled by the Russian and British empires. Reza Khan (see Reza Shah Pahlavi
) seized power in a coup (1921). His son Mohammad Reza Shah Pahlavi
alienated religious leaders with a program of modernization and Westernization and was overthrown in 1979; Shi'ite cleric Ruhollah Khomeini
then set up an Islamic republic, and Western influence was suppressed. The destructive Iran-Iraq War
of the 1980s ended in a stalemate. Since the 1990s the government has gradually moved to a more liberal conduct of state affairs.